The world renowned novelistMark Twain(Samuel Clemens) died in Reading, Connecticut, on April 21, 1910, but he is far from forgotten. Especially with Hal Holbrook around.

Holbrook's Mark Twain Tonight is a bona fide phenomenon – the longest-running solo act in theatre history. The one-man show, which has now been going for more than 60 years, earned the actor a Tony Award in 1996. Dates are already lined up throughout 2016 for Holbrook's extravaganza.

In 2014, his show was celebrated in a documentary film by Scott Teems called Holbrook/Twain: An American Odyssey, which was the opening film of the five-day American Film Institute's international documentary festival.

Holbrook was at the screening in Washington and said: "I just can't thank people enough for coming together and putting this film together."

"Age is an issue of mind over matter. If you don't mind, it doesn't matter," said Twain, the author of Huckleberry Finn and Tom Sawyer, and Holbrook, who was born in Cleveland, Ohio, on February 17, 1925, might agree. He is now 91 and has already lived 17 years longer than Twain, who was superstitious about death. Halley's comet appeared in 1835 when he was born and he always said he would die when it appeared again – and he did, at the age of 74.

Shot in black and white over five years, Holbrook/Twain: An American Odyssey incorporates segments of the show, in which Holbrook, in a white waistcoat, moustache and false nose and puffing from a cigar, recites from memory entire passages from Twain's substantial collection of writings. Fellow actors Martin Sheen, Emile Hirsch and Sean Penn make cameo appearances in the documentary, alongside Holbrook's children over three marriages and a small posse of admiring Twain scholars. Holbrook/Twain is also a love story about Holbrook and his third wife, Dixie Carter, who died four years ago after 26 years of marriage.

Mark TwainCredit:
Rex Features

Holbrook, who first performed Twain at State Teachers College at Lock Haven, Pennsylvania in 1954, has taken his show to 50 states in America, as well as 20 countries abroad, and performed the show for five presidents. "I wanted this thing to be good, but I didn't want it to take over my life," he says during the documentary.

"Mark Twain gets me out of the bed in the morning," Holbrook, who has won five Emmys and earned an Oscar nomination for the 2007 film Into the Wild, once said. "He literally fires me up. I don't have to fire myself up, all I have to do is lay there and think about what's going on in my country and the world and run over some Twain I am going to do."

Asked by the LA Times once what he thought of rivals who played Twain, he joked: "I try to track them down and make sure they aren't stealing my show," adding that Twain's humour was timeless. "I don't know if there's anybody in our history who understood and appreciated our American character more than Mark Twain, but he was a critic of our behaviour, and of the behaviour of the entire human race," he said.